Technically, no. The demo was delisted from PSN years ago. If you have a PS3 with the demo still installed from 2010, you are sitting on digital archaeology.
However, the God of War III Remastered (PS4) includes the full game. While the specific "Caverns" demo is gone, the Remastered version runs at 60fps and includes all the bonus costumes that the demo teased. Download God Of War 3 Demo
Unlike modern demos that throw you into a random mid-game level, the God of War III demo showcased a bespoke slice of the game: The Caverns. Technically, no
Kratos starts on a rocky precipice overlooking a massive chain linking the underworld to Mount Olympus. You had the full moveset—Apollo’s Bow, the Cestus (fists), and the trusty Blades of Exile. The demo was a 20-minute gauntlet of: Note: This is not a “download” but a stream
Note: This only works if you added the demo to your account during its active period. Many users report that even historical downloads fail due to expired authentication tokens. However, it is worth trying.
Note: This is not a “download” but a stream. It requires a high-speed internet connection (at least 15 Mbps).